Safety device for vehicle seats

ABSTRACT

A vehicle safety device for reducing whiplash in a vehicle includes a curved guide configured to allow a seat to slide thereon, an impact sensor that can detect an impact on a rear end of the vehicle; and a locking mechanism that can allow the seat to slide on the curved guide when an impact is detected by the impact sensor. The locking mechanism can prevent the seat from moving relative to the curved guide when there is no impact detected by the impact sensor.

BACKGROUND OF THE INVENTION

The present application relates to vehicle technologies, and inparticular, to technologies that assure safety of drivers and passengersin vehicles such as cars and buses.

Whiplash is a relatively common injury that occurs to a person's neckfollowing a sudden acceleration-deceleration force, most commonly frommotor vehicle accidents. The term “whiplash injury” describes damage toboth the bone structures and soft tissues, while whiplash associateddisorders (WAD) describes a more severe and chronic condition. Althoughwhiplash is typically not a life threatening injury, it can lead to aprolonged period of partial disability. There are significant economicexpenses related to whiplash that can reach a huge amount of moneyincluding: medical care, disability, sick leave, lost productivity, andlitigation. Whiplash is most commonly caused by a motor vehicle accidentin which a person is riding in a stationary or slow moving car that isstruck by a vehicle from behind without notice. It is commonly thoughtthe rear impact causes the passenger's head and neck to be forced intohyperextension as the seat pushes the person's torso forward—and theunrestrained head and neck fall backwards.

Despite advances in safety devices, neck injuries in traffic accidents,especially non-severe rear impact accidents, are still a serious andcostly social problem. The high cost of whiplash injury has beenextensively documented. The development of safety measures to reducewhiplash injuries has been the source of many research investigations.Most of these research projects tried to provide an understanding ofhead-neck kinematics during low energy rear-collisions. This led to theintroduction of head restraints since the 1960 's as a countermeasure tolimit relative motion between the head and thorax, thereby reducinginjuries.

However, the effectiveness of these devices in reducing automotiveinjury has been limited. This is thought to be caused by the incorrectposition of the head restraint. The first generation (unadjustable) headrestraints were not optimally placed considering human anthropometry toprevent relative head-neck motions although they may have enhancedhead-neck relative motion during rear collision. After being introduced,adjustable head restraints were found usually not positioned correctlywhich made them inefficient. Besides, even when used in their optimallocations, they have a limited benefit in reducing injuries becausetheir static behaviors are often not adapted to the occupants' headpositions at the times of the impact events.

There is therefore a need for improved designs for the safety devices onvehicles.

SUMMARY OF THE INVENTION

The presently disclosure attempts to address the aforementionedlimitations in conventional vehicle safety devices. The presentlydisclosed method is significantly more effective in reducing whiplashinjuries than conventional safety devices.

In one aspect, the disclosed method seeks to reduce forces exerted onpassenger's head during whiplash motions by minimizing the total angularacceleration and thus the angular displacement of the passenger's head.The sudden expansion of neck muscles and vertebrates are reduced byintroducing a negative acceleration on the passenger's body. Thenegative acceleration is provided by a curved guide underneath the seat,which can generate a tangential and a normal acceleration in thepassenger's head. Since the normal acceleration does not cause whiplashinjury, the total original acceleration is reduced by the amount of thisnormal acceleration.

Moreover, an impact sensor can be mounted at the rear end of a vehicle,which, upon impact from behind, can activate the disclosed whiplashreducing device to allow the seat to rotate freely. When there is norear impact, the seat returns to a normal position in which the seat islocked down and not allowed to rotate freely.

In one general aspect, the present invention relates to a vehicle safetydevice for reducing whiplash in a vehicle, which includes a curved guideconfigured to allow a seat to slide thereon; an impact sensor configuredto detect an impact on a rear end of the vehicle; and a lockingmechanism that can allow the seat to slide on the curved guide when animpact is detected by the impact sensor, wherein the locking mechanismcan prevent the seat from moving relative to the curved guide when thereis no impact detected by the impact sensor.

Implementations of the system may include one or more of the following.The vehicle safety device can further include a signal conditioningcontroller that can produce a control electric signal in response todetection of the impact by the impact sensor. The signal conditioningcontroller can produce the control electric signal having a waveformtailored to the vehicle. The signal conditioning controller can producethe control electric signal having a waveform tailored to properties ofthe impact. The signal conditioning controller can produce the controlelectric signal having a waveform tailored to properties of thepassenger. The locking mechanism can lock the seat to the curved guidewhen there is no impact detected by the impact sensor. Tin the lockingmechanism can include a locking pin that is configured to lock the seatto the curved guide when there is no impact detected by the impactsensor and to unlock the seat from the curved guide when there is animpact detected by the impact sensor. The locking mechanism can includea solenoid that can control movements of the locking pin in response towhether an impact is detected by the impact sensor. The vehicle safetydevice can further include balls between the seat and the curved guide,which allows the seat to freely slide on the curved guide.

These and other aspects, their implementations and other features aredescribed in detail in the drawings, the description and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating a car without a whiplashcontrol mechanism.

FIG. 2 is a detailed schematic diagram illustrating the car without awhiplash control mechanism in FIG. 1.

FIG. 3 shows experimentally measured and simulated head angles during awhiplash event in a vehicle without a whiplash control mechanism asshown in FIGS. 1 and 2.

FIG. 4 is a schematic diagram illustrating a car installed with awhiplash reducing device in accordance with the present invention.

FIG. 5 is a detailed schematic diagram for the whiplash reducing deviceof FIG. 4.

FIG. 6 illustrates a temporal force profile applied to a car without awhiplash control and a car installed with the presently disclosedwhiplash reducing device.

FIGS. 7A-7D show comparisons of car speeds, car displacements, seatrelative speeds, and seat relative displacements between a car without awhiplash control (solid lines) and a car installed with the presentlydisclosed whiplash reducing device (dashed lines).

FIGS. 8A-8D show comparisons of passenger head angles, head angularaccelerations, head horizontal accelerations, and head verticalaccelerations between a car without a whiplash control (solid lines) anda car installed with the presently disclosed whiplash reducing device(dashed lines).

FIGS. 9A-9B show seat angles and angular speeds in a car installed withthe presently disclosed whiplash reducing device.

DETAILED DESCRIPTION OF THE INVENTION

The presently disclosure aims to overcome drawbacks in the abovedescribed conventional car safety devices.

The whiplash mechanism is modeled using a linear spring and dampers torepresent the head and neck of a human body sitting in a standing car.The movements of the head and the neck are caused by a rear impact tothe standing car. Two cases have been modeled; a car seat withoutwhiplash control mechanism; and a car seat installed with an inventionwhiplash control mechanism.

Referring to FIG. 1, a conventional car 100 without whiplash controlincludes simplified mass blocks for a car body 110, a seat 120, an upperbody 130, a head 140, a seat spring 150, a seat damper 160, a tirespring 170, and a tire equivalent damper 180.

In the present disclosure, the conventional car without whiplash controland the vehicle installed with the invention whiplash reducing deviceare modeled.

The following parameters are chosen in simulations of the conventionalcar 100: the mass of the car 100: m_(c)=1400 kg; tire equivalent damper180:

${C_{t} = {20000\mspace{14mu} {N \cdot \frac{s}{m}}}};$

tire equivalent spring 170:

${K_{t} = {1\frac{N}{m}}};$

the combined mass for the seat 120 and the upper body 130: m_(s)=100 kg;damping factor for the seat damper 160 C_(s)=100000 N.s/m; seatequivalent spring 150:

${K_{s} = {100000\mspace{14mu} \frac{N}{m}}};$

the neck length r=0.2 m; the mass of the head 140 m_(h)=3 kg; neck-headequivalent torsional damper C_(tn)=5 N.m.s/rad; neck-head equivalenttorsional spring K_(tn)=20 N.m/rad.

The simulations are verified using experimental data. As shown in FIG.3, the head angle and obtained from simulations shows a similar whiplashbehavior to the data measured in the experiments.

Referring to FIGS. 4 and 5, a vehicle 400 in accordance with the presentinvention includes a vehicle body 410, a seat 420, an upper body 430, ahead 440, a tire spring 470, and a tire equivalent damper 480. Thevehicle 400 further includes a whiplash reducing device 500 whichincludes a curved guide 510, balls 520, an impact sensor 530, a signalconditioning controller 535, and a locking mechanism 540. The impactsensor 530 can be mounted on the rear bumper of the vehicle 400. Theseat 420 is mounted on the curved guide 510 and with the seat's weightsupported by the curved guide 510. The balls 520 are mounted between theseat 420 and the curved guide 510, which allow the seat 420 to glidealong the curved guide 510. The locking mechanism 540 is in wired orwireless communication with the impact sensor 530. The locking mechanism540 can include a locking pin 545 that is controlled by a solenoid (notshown) under the control of an electric voltage. Under the control of anelectric signal, the locking pin 545 can be moved by the solenoid to alocking position to lock the seat 420 to the curved guide 510 or to anunlocked position to allow the seat 420 to move along the curved guide510.

When an impact is detected by the impact sensor 530 due to a collisionby another car at the rear end of the vehicle body 410, the impactsensor 530 sends a sensing electrical signal to a signal conditioningcontroller 535. In response, the signal conditioning controller 535produces an control electric signal having a waveform that is tailoredto the vehicle (weight, height, length, materials, configurations,etc.), the properties of impact (acceleration, direction, etc.), thepassenger (weight and height, etc.) and sends the control electricsignal to the locking mechanism 540. In response, the solenoid in thelocking mechanism 540 unlocks the locking pin 545, which allows the seat420 to slide on the curved guide 510. When there is no impact detectedby the impact sensor 530, the solenoid moves the locking pin 545 into alocking position which secures the seat 420 to a sturdy position. Thewhiplash reducing device 500 also includes a seat torsional spring 550and a seat torsional damper 560, which are used to optimize the dynamicresponse of the seat 420 and the passenger in response to the impact. Asa result, whiplash is effectively reduced in the passenger's head 440and the upper body 430. When there is no impact detected by the impactsensor 530, the locking mechanism 540 can lock the seat 420 to thecurved guide 510, preventing it from moving relative to the curved guide510.

The mass of the vehicle 400, the seat 420, the upper body 430, the head440, the tire spring 470, and the tire equivalent damper 480 aresimulated using the same parameters as their counterparts in FIG. 1 asdescribed above. In addition, the following parameters for the whiplashreducing system 500:

Mass moment of inertia of the seat 420 and the upper human body 430J_(s)=250 kg.m²; seat torsional damping constant: S_(td)=900 N.m.s/rad;torsional stiffness of the seat torsional spring 550: S_(ts)=50 N.m/rad;the radius of the curved guide 510: R=2 m; the distance between head andseat sliding curve: H=0.8 m; the distance between seat and the curvedguide 510: h=0.1 m.

After solving the nonlinear equation of motion using Rung-Kuttatechnique, the car or vehicle, seat, head and neck motion are simulatedusing the following parameters: f₀=4(10)⁵N, t₀=50 ms, where f₀, t₀ arethe peak value and duration of a force applied to the rear end of thecar or vehicle. As shown in FIG. 6, the force can approximately have theshape of half cycle of a sine curve.

The simulation results for the conventional car (shown in FIGS. 1 and 2)and the vehicle installed with the whiplash reducing device (FIGS. 4 and5) are compared in FIGS. 7A-8D. FIGS. 7A-7D show comparisons of carspeeds, car displacements, seat relative speeds, and seat relativedisplacements between a car without a whiplash control (solid lines) anda car installed with the presently disclosed whiplash reducing device(dashed lines). While the car speeds and displacements are similar forthe convention and invention vehicles, the seat speeds and displacementsrelative to the car are very different for the two systems. Thedisclosed whiplash reducing device has produced a significant negativemovement (speed and displacement) in the seat relative to the vehiclebody, which compensate the forward movement of the vehicle. While thevehicle displaced by a distance of 0.63 m, the maximum relative seatdisplacement relative to the vehicle body is 28 cm. The net effect ofthe disclosed whiplash reducing device is thus to drastically reduce themovement of the upper body and the head of the passenger.

FIGS. 8A-8D directly compare the impacts on the passengers between theconventional car (shown in FIGS. 1 and 2) and the vehicle installed withthe whiplash reducing device (FIGS. 4 and 5). As shown, the inventionvehicle (dashed lines) have much smaller magnitudes in passenger headangle, head angular acceleration, head horizontal acceleration, and headvertical acceleration than those in a conventional car without awhiplash control (solid lines). The maximum head angular acceleration isreduced from 4.4×10⁴ deg/s² in the conventional car to 1.44×10⁴ deg/s²in the invention vehicle. The maximum head linear acceleration in thehorizontal direction is reduced from 16 g and reduced to 14.9 g.

Referring to FIGS. 9A-10B, the seat 420 has moved along the curved guide510 by a maximum of −8.5 degrees (i.e. backward motion relative to theforward impact on the rear-end of the vehicle).

While this document contains many specifics, these should not beconstrued as limitations on the scope of an invention that is claimed orof what may be claimed, but rather as descriptions of features specificto particular embodiments. Certain features that are described in thisdocument in the context of separate embodiments can also be implementedin combination in a single embodiment. Conversely, various features thatare described in the context of a single embodiment can also beimplemented in multiple embodiments separately or in any suitablesub-combination. Moreover, although features may be described above asacting in certain combinations and even initially claimed as such, oneor more features from a claimed combination can in some cases be excisedfrom the combination, and the claimed combination may be directed to asub-combination or a variation of a sub-combination.

Only a few examples and implementations are described. Otherimplementations, variations, modifications and enhancements to thedescribed examples and implementations may be made without deviatingfrom the spirit of the present invention. For example, the disclosedsafety mechanism or device is applicable to many types of vehicles suchas cars, buses, trucks, etc. The parameters of the various components inthe vehicles are not limited to those used in the simulations described.Moreover, the disclosed whiplash reducing device is suitable to work inconjunction with many other types of seat safety devices such as seatbelt and should straps.

What is claimed is:
 1. A vehicle safety device for reducing whiplash ina vehicle, comprising: a curved guide configured to allow a seat toslide thereon; an impact sensor configured to detect an impact on a rearend of the vehicle and to produce a sensing signal; a locking mechanismconfigured to lock the seat to the curved guide when there is no impactdetected by the impact sensor, wherein the locking mechanism isconfigured to unlock the seat to allow the seat to slide on the curvedguide after the sensing signal is produced by the impact sensor; and aseat torsional damper coupled to the seat to damp the seat's movement.2. The vehicle safety device of claim 1, further comprising: a signalconditioning controller configured to produce a control electric signalin response to the sensing signal from the impact sensor, wherein thelocking mechanism is configured to unlock the seat in response to thecontrol electric signal.
 3. The vehicle safety device of claim 2,wherein the control electric signal has a waveform tailored to thevehicle.
 4. The vehicle safety device of claim 2, wherein the controlelectric signal has a waveform tailored to properties of the impact. 5.The vehicle safety device of claim 2, wherein the control electricsignal has a waveform tailored to properties of the passenger.
 6. Thevehicle safety device of claim 2, wherein the signal conditioningcontroller produces the control electric signal to limit the seat'sangular displacement along the curved guide to be smaller than 8.5degrees after the sensing signal is produced by the impact sensor. 7.The vehicle safety device of claim 1, wherein the locking mechanismcomprises: a locking pin that locks the seat to the curved guide whenthere is no impact detected by the impact sensor and unlocks the seat toallow the seat to slide on the curved guide after the sensing signal isproduced by the impact sensor.
 8. The vehicle safety device of claim 7,wherein the locking mechanism comprises: a solenoid configured tocontrol movements of the locking pin between a lock position and anunlock position in response to whether the sensing signal is produced bythe impact sensor.
 9. The vehicle safety device of claim 1, furthercomprising: balls between the seat and the curved guide, which allow theseat to slide on the curved guide when the seat is unlocked by thelocking mechanism.
 10. The vehicle safety device of claim 9, wherein theseat torsional damper damps movements of the balls.
 11. The vehiclesafety device of claim 9, further comprising: one or more seat torsionalsprings configured to provide torsional stiffness to the seat'smovement.
 12. The vehicle safety device of claim 11, wherein each of theone or more seat torsional spring is coupled between two of the ballsbetween the seat and the curved guide.